Session in Generic Handler

I'm setting a session variable in generic handler
context.Session.Add("test", "value");
 and accessing it in another generic handler but getting null. i alse have import namespace "IRequiresSessionState"
string sessionvalue = context.Session["test"].ToString();
Session state mode in web.config is "SQLServer".
<sessionState mode="StateServer" sqlConnectionString="my connection string" cookieless="false" timeout="50"/>
When I change session state mode to "InProc"
<sessionState mode="InProc" cookieless="false" timeout="50"/>
 Its working fine. but i want to use "SQLServer" session state mode.
Any help/solution?
Thanks in advance
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